Hi
No
A definite NO
Pretty much all classic drugs are banned in Thailand and the risks are very high.
You may hear that "cocaine and opium" were legalized last year, but that's only in research contexts.
If you get caught with any of those in your system, you go straight to jail.
Even if you're seriously in pain, the best you can hope for is usually paracetamol.
Kratom was legalized in August, so this one is legal for real.
The country is trying to cash on hemp and kratom production, but if you get caught even with CBD without an authorization, straight to jail.
Plants and products with more than 0.2% of THC content are illegal. Have fun eating a kilo.
There were talks of legalizing meth a few years back, but they went up in smoke.
Bottom line: only do drugs in Thailand if you're sure you won't get caught.
Ketamine used to be available in India, but I don't know about the current situation.
I went there several years ago, and I didn't find any (I didn't search that much)